data 和 metadata

昨天提交的数据库作业是有关于读data和metadata的思考的。

从网上搜到的资料大多的意思就是data是包含信息的，metadata是用来描述data的data。那么到底什么是data啊，或许我不应该问这个问题，就像我问什么是cat一样，cat就是一种很萌的动物啊。

Data has a lot of definition, but overall it is a kind of information. Data is a fact that people already known and people can get information form data. To store data, we have to organize data in a particular form, sometimes in the form of binary.

Metadata are data about the data in the database. Metadata describe the name given and the length assigned to each data item. Metadata also describe the length and composition of each of the records. Metadata includes a description of what the value of each data item looks like.

For example, when we establish a database about students’ grades. Usually we call the grades itself is data and the data to describe the grades’ subject, semester, highest sore etc. is metadata.